London Midland said it would be putting on replacement buses where possible
Rail passengers have been warned to expect delays after all of London Midland's services across England this Sunday were cancelled.
Working on Sundays is voluntary for most London Midland workers. The firm said a large number of staff had failed to volunteer for Sunday 6 September.
A spokesman for the company said it would be putting on replacement bus services where possible.
It provides services from London, through the Midlands to the North West.
The spokesman said he was unsure of any particular reasons why the firm was facing a staff shortage this Sunday.
In July, the Rail, Maritime and Transport union announced it would be balloting its members over strike action regarding Sunday pay.
The union said station, clerical, retail, booking office and supervisory staff did not receive the same pay for Sundays as drivers.
The train firm operates more than 1,200 services a day through London, Hertfordshire, Buckinghamshire, Bedfordshire, Northamptonshire, Warwickshire, Staffordshire, Herefordshire, Worcestershire, the West Midlands, Shropshire, Cheshire and Merseyside.